The present invention relates to a PIM sensitive diplexing or multiplexing filter and more particularly to an interface for the coaxial common port of a diplexing or multiplexing filter.
A common coaxial transmission line must be connected to the resonating elements of a filter section in such a manner as to reliably avoid the production of passive intermodulation (PIM) . The highest reliability in the avoidance of PIM is accomplished by coupling the transmission line and the filter in a non-contacting, or xe2x80x9cisolatedxe2x80x9d configuration, i.e. a capacitive joint and/or an inductive joint. However, while this electrical isolation avoids PIM, it introduces other problems. For example, there is no bleed path for electrostatic charge build-up. Another potential problem is a build up of heat from poor heat dissipation of the inner conductor because there are no conduction paths that are inherent with xe2x80x9cdirectlyxe2x80x9d contacting conductors.
In an attempt to overcome these problems, a thermal shunt, or other thermally conductive path consisting of a direct electrical and thermally conductive path between the inner conductor and the outer conductor has been added to the interface. This requires that the inner conductor of the PIM sensitive hardware must be intimately attached to the outer conductor. At least one fastening attachment, such as a screw, is normally used. Unfortunately, this assembly is not very reliable in terms of PIM avoidance.
There is a need for a PIM sensitive diplexing-filter common interface that provides PIM reliability in conjunction with ESD conduction and thermal dissipation, making it ideal for high power space applications.
The present invention is a one-piece interface connector for a PIM sensitive diplexing filter. In the present invention there is an absence of contacting connections of the inner-conductor. The inner-conductor and outer-conductor are one piece, thereby eliminating any direct metal-to-metal connections to the high current carrying inner-conductor. The only direct connection is to the outer-conductor that can be connected by any means proven to have high reliability in the avoidance of PIM generation, such as a high-pressure connection.
The present invention allows the transfer of high power RF energy from the resonating element of a cavity resonating filter to another component, such as an antenna feed element. The transfer is such that it avoids the risk of PIM generation while providing a thermally conductive path and an electrostatic conductive path to dissipate heat and dissipate static electric charges from the transmission line inner conductor.
The inner-conductor of the interface is integral with the outer-conductor of the interface, thereby eliminating any need to connect the inner-conductors of the interface to the outer conductor. The outer-conductor of the interface has flange, or other structure, which allows for a connection to the outer-conductor of a transmission line or filter housing. The result is a xe2x80x9cone-piecexe2x80x9d construction of a diplexed, (or multiplexed), coaxial, (or squareax), transmission line so as to provide a direct path for thermal dissipation and ESD ground and having a non-contacting, integral inner-conductor interface.
It is an object of the present invention to transfer high power RF energy from a resonating filter to another component. It is another object of the present invention to avoid the risk of passive intermodulation generation. It is yet another object of the present invention to provide a conductive path to dissipate heat and static electric charges.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.